Password protect a PDF
Encrypt a PDF with AES-256 so it cannot be opened without the password — done entirely on your device, which is the only way a password tool should work.
- Processed on your device
- No upload, no waiting
- No signup, no watermark
How it works
Add your PDF
Drop the document you want to lock.
Choose a password
Type it twice. Optionally decide whether printing, copying and editing are allowed.
Download
Your encrypted PDF asks for the password in every reader, on every device.
Frequently asked questions
How strong is the encryption?
AES-256 with revision 6 key derivation — the strongest the PDF format defines, and the same standard Acrobat uses. The password is put through a deliberately slow hash designed so that graphics cards cannot speed up guessing it.
Is my file or password uploaded?
Neither, and this is the tool where that matters most. Everything happens in your browser, so your document and the password that protects it are never both in someone else's hands. A site that encrypts on its server has, by definition, seen both.
What if I forget the password?
The file is gone. There is no recovery, no back door and no master key — that is what makes the encryption worth anything. Write the password down somewhere safe before you send the file.
What do the permission settings actually do?
They tell reader software what to allow — printing, copying text, editing. Be clear-eyed about them: they are requests, not encryption, and any determined person can ignore them. The open-password is the part that genuinely protects the document.
Will it open on a phone, in Acrobat, in Chrome?
Yes. It is standard PDF encryption, so every modern reader on every platform will prompt for the password and open it.
Can I protect a PDF that is already protected?
Remove the existing password first with Unlock PDF, then protect it again with the new one.
Good to know: A password is only as good as its strength: a short or common one can be guessed offline by anyone who has the file. Use something long. Permission settings (print, copy, edit) are advisory and honoured only by well-behaved readers.